Method of making bearings



June 24, 1930. G. R. SHORT METHOD OF MAKING BEARINGS Filed May 5, 1927 QLza Patented June 24, 1930 UNITED STATES,-

crrmns a. snow, or nnrnorr, mcnrom, nssreuoa are THE MORAI'NE rnonucr's- PATENT oFFlCE- CORCPORATION, OF DAYTON, OHIO, A CORPORATION OF OHIO METEQID MAKING BEARINGS Application filed m '5, 1927. Q Serial No. 188,930.

This invention relates to the manufacture of articles having surfaces adapted to be placed in rubbing contact with a relatively movable'part such as a bearing for' a shaft or a guide-for alreciprocating part.

One object of the present invention is to provide an improved method of making a bearing, guide or similar part comprising a contact portionof relatively'porous metal capable of containing a-lubricant and a portion of metal of relatively high mechanical strength.

Briefly, this object is accomplished by forming a relatively thin sheet or plate of porous metal and permanently attaching it to the piece of stronger metalwhich serves as a support and'r'eenforcement for the porous metal. In my 'copending application, Serial N o. 188,929, filed 'May 5, 1927, I have disclosed the manufacture of a machine element having a flat bearing surface. This element is made by first forming a thin sheet ofporous v metal in a manner which I shall describein detail later; andthen joining the sheet of porous metal to the plane surface of a body of relatively dense, strong metal by a bond which is substantially coextensive with the contiguous surfaces of the united parts. Such a machine element may 'be"used as a thrust hearing or a 'gib. p

' In this applicationI'sh'all disclose the man- 'ufacture of a machine element having a curved or cylindrical bearing surface which is provided by bending a flat sheet offporous metal into the desired shape, and then joining it to a suitable cylindrical surface provention is clearly shown.- I

In the'drawingsr 4 l Fig. 1 is an edge viewof a thin sheet of porous metal; v 4 V Fig. 2 is a sectional view showinglan apvided by a reinforcing member of denser,

paratus for bending the porbus metal sheet into a preliminary form;

.Fig. 3 is a view partly in section showing apparatus for bending the porous metal sheet into final form;

Fig. 4 is a fragmentary view, artly in section, of a connecting rod provided with a bearing according to the present invention; Fig. 5jis a side view of apparatus used in manufacturing the elements of a shaft hearing, for example, one of the main bearings of .an engine crank shaft; and

Fig. 6 is a perspective view of a bearing part shown in F5.

' The porous metal plate designated by numer'al 20 in Fig; 1 is preferably constructed by briquetting a mixture of bronze forming metal powders, a filler such as graphite and a volatile void forming substance such as salicylic acid, and then sintering this form under nonoxidizing conditions at a temperature and for a time sufiicient to cause the metal particles to unite and the void forming substance to volatilize and to produce a metal structure v interspersed with a number of minute intercommunicating voids for receiving lubricant.

Examples of the manufacture of porous metal are'disclosed in Patent 1,642,347, issued Sept. 13, 1927, to H. M. Williams.

' Before the bearing plate can be'used as a shaft journal or crank-pin bearing, it is bent' into semi-cylindrical form by use of the apparatus shown in Figs. 2 and 3. Fig. 2 shows a. block 21 provided-with a straight groove 22 I mergingv with a semi-circular groove 23 which partly surrounds a cylindrical plug 24 whichis supported by the block 21, but may be removed therefroma; The 'plate- .20 is pushed into the groove'22 and then into the.

groove 23 in order to give it a semilindrical shape. The plug 24 may be wit drawn from the block to facilitate removal of the plate-20. On being removed, the plate 20 I will spring out of shape,-'so that a further operation to give .it a final form isrequ red. This operation is performed by squeezing the plate 29, betweenrelatively-movable members- 25 and 26 shown in Fig.3.- Itihasbeen 'found'desirableto use the apparatus shown in Fig. 2 t o perform a preliminary bending step because the matepial is relatively weak in tensile strength and if subjected while inthe flat state to the action of members 25 and 26 i the tensile strain to which it is subjected which has been described is particularly suits jg able on account of the character of the mamight be so great at certainv points as to destroy the sheet entirely. The apparatus of- -Fig. 2 overcomes this difliculty by causing.

the piece tobe bentgradually from flat to v I cylindrical form.

While the porousmetal plate may be bent in other ways into the desired form, the one terial work ed u on. There is considerable resistance offere to'the forcing of the plate -through'thegrooves 22 and 23 due to friction between the plate'and the walls of the o'oves. As the porous metal is being bent 1t is being compressed to a substantial degree in the direction of its movementthrough the grooves. This compressing or compacting of the structurev of the porous. metal tends to offset the tendency to pull apart those por- 'tions which would ordinarily be in tension during the bending operation. In other words the compacting of the-plate overcomes its tendency to crack at its surface of greater curvature. Due to its porosity the plate 20 can be compacted to a substantial degree as it is driven through the grooves 22 and 23;

therefore the method of, bending disclosed herein has proved satisfactory.

The curvature of the mandrel 24 is preferably substantially the same as that of the radius than. emandrel, when the plate is removed from the groove 23.

Although preferable, it is not necessa that the, groove 23 be a semiwylinder. t

might bea segment of a cylinder and have an angular extent suflicient only to cause the plate to take a permanent set. It is desirable angular extent because the greater the frictlonal resistance to the movement, of the plate cylindrica 20 into the grooves 22 and 23 the greater will be the tendency to compact the platewhile it is being bent, thus preventing cracking as explained in the second preceding paragraph. v

Fi 4 shows the applicaton'of semi-cylindrica bearings to the crank-pin end of .a connectin rod. A connectin rod 30 is provided wit a cylindrical sur ace.31' adapted to. receive the porousmetal bearing of a pre determined thickness, and a connecting-rod cap 32 is provided with a similarly formed surface .33. The surfaces 31 and 33 are coated with a metal, for example tin, which is adapted to alloy, bond or unite with the metal ofthe connecting-rod cap, ferrous but this is not essential. The mandrel.

stgring to a curvature ofgreater' metal for example, and to alloy with the porous metal bearing part 20, which is preferably of porous bronze. The tin coat is indicated at 34 and 35 on Fig. 4, but it will be understood that this drawing greatly exag gerates the thickness of the tm coat. For a good bond thiscoat should be uniform but as thin as possible. The bearing parts 20 are assembled as shown in Fig. 4 between the connecting rod 30 and the cap 32 and a mandrel 36 which is substantially the same diameter as the crank pin for which the connecting rod is intended to be used. The assembly is clamped about acylinder 36 by bolts 37 and nuts 38; and, while thus assembled, the assembly is heated to a temperature sufficient to cause the tin or other coating to unite. with the bearing parts. as well aswith the connecting rod parts. After the assembly is cooled, the clamping bolts are removed leaving the bearing part 20 permanently oined to a connecting rod part.

The bearing 20 may be impregnated with lubricant by immersing the entire structure in a bath of hot .oil, or they may absorb some of the excess oil which is delivered to the cra'raik pin with which the, connecting'rod is use The heating of the assembly is performed preferably in a bath of molten salts having a melting pointof a proper temperature.

Figs. Sand 6. show the method of manufacturing two-part bearings for shafts such as the crank-shafts of englnes. A flat sheet of porous metal is bent into semi-cylindrical form 40 and laced against the bond coating 41 of a previously coated reinforcing shell Two of these assemblies are clamped 'agains't'a cylinder 47 and between'two clamps 43 and 44 by tightening the nuts 46 on the bolts 45 which pass through the clamps. This assembly is heated to a temperature suflicient to melt the bonding metal 41 and to cause it to alloyor unite with the metal of the [shells 42 and the metal of the bearings 40. After cooling the assembly the clamps are reowever to use a groove having the maximum ent invention-as herein disclosed, constitutes a preferred form,it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

- What is claimed is as follows:

shafts and the like which comprises: forming a relatively thin, flat plate having a porous metallic structure forming the porous plate 1.-The method of making a bearing for 4 I bearing lining of a porous metallic structure,

2. The method of making a bearin for shafts 'and'the-like which com rises: orming a relatively thin plate havmg a porous metallic structure, gradually forming the porous plate into cylindrical form while in detached condition, and then attaching the formed porous plate to a preformed metal reinforcingbody by a metallic'bond which is substantially coextensive with the contiguous surfaces of the bodies.

3. The method of making a. bearin for shafts and the like, which comprises: orming to approximately final shape a detached inserting this'porous lining into acorrespondingly shaped bearing back having its contacting metal surface adapted to alloy with said aprons lining, clamping said porous in 111 surface contact with said bearing back by means of an arbor fitting within" said lining, and then heat-treating this assembly to cause the porous lining to unite with the metal of the bearing back.

4. The method of making a bearing for shafts and the like, which comprises: forming to approximately final shape a detached bearing hnlng of a porous metallic structure, inserting this porous lining into a correspondingly shaped bearing back having its contacting metal surface coated with a metal having an aflinity, to said porous lining clampmg' said porous g in firm surface contact with said coated surfa'ceof the hearing back by means of an arbor fitting within said lining, and then. heat-treating this assembly to cause the orous lining to unite with the-metal of the aring ba'ck.

signature 'In testimony whereof I hereto afiix my CHARLES 3'. SHORT. 

